Multipla New member, got a problem already

[Pam]

Hi, I'm a new member and also a non-mechanical woman.... so go easy!
My 2005 Multipla 1.9 diesel has an intermittent loss of power problem. Went into my local garage who couldn't find anything on a short test drive. It goes well, but then will start to fade; revs dropping gradually. Sometimes comes back to life over the brow of a hill, but sometimes I have to drop into third gear to get the revs coming back, suddenly. Usually this is after some time driving, but sometimes it lacks power just after starting in a car park. engine sounds smooth, not missing or coughing, just no oomph. Drove home from the Alps yesterday, got here OK, but this loss of power was a feature. Would go absolutely fine for an hour (despite torrential rain and spray), then just fade, sometimes when driver eased off to drop speed, for example when behind a truck waiting for a gap to overtake.

Any suggestions?

 

[widemouthfrog]

Sounds like the MAF (mass airflow sensor). You can try cleaning it (which is a bit tricky, but cheap) or replace it. Don't be tempted to buy a cheap copy unit from ebay as they are rubbish - go with a genuine Bosch one. Cheapest place seems to be an online seller in Germany that will ship to the UK. Cost is around £90-100including delivery when I last looked.

Fitting it is relatively simple. It shouldn't take more than 20 minutes to put a new one on.

Cleaning the original one may be worth a try. The bit that gets dirty is extremely fragile and should not be touched with your fingers. However, it's protected by a large housing on top of the engine. Unplug and remove the housing complete, put it in a carrier bagged plastic bag (make sure there aren't any holes in it), pour in a small glassful of isopropyl alcohol or methylated spirits, twist the bag shut, then shake the hell out of it for a few minutes. It's a bit like making your own miniature washing machine. Let the MAF dry out well before refitting it. IPA or meths don't take long to evaporate.

A faulty MAF will often not flag up a fault code when the car is hooked up to a diagnostic machine. To check if it's the cause of your problem, unplug it and go for a drive. There's a thread on here with a photo to show its location, but I can find it ATM.

 

[cooky257]

If its not the maf, then i would look at the egr valve, when was it last cleaned.